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Energy-efficient
refurbishment of
existing housing
CE83
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2 Energy-efficient refurbishment of existing housing (2007 edition)
Contents
1 Introduction 3
2 Best practice summary 6
3 Energy Saving Trust technical recommendations Insulation standards 9
4 Energy Saving Trust technical recommendations Ventilation 19
5 Energy Saving Trust technical recommendations Airtightness 21
6 Energy Saving Trust technical recommendations Space heating and hot water 23
7 Energy Saving Trust technical recommendations Lights and appliances 27
8 Renewable and low-carbon technologies 30
9 Embodied energy 32
10 Energy Saving Trust best practice guidance 33
11 Further information 34
12 Publications 36
Cover image Nelson refurbishment scheme courtesy of Pendle Borough Council.
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Energy-efficient refurbishment of existing housing (2007 edition) 3
1 Introduction
The minimum standards set by building regulations
varies across the UK. The following guidanceshould be consulted to determine the different
technical performance requirements, definitions and
procedures:
Communities and Local Government offers
a series of approved documents containing
guidance on compliance in England and Wales.
Part L deals specifically with the conservation of
fuel and power.
The Scottish Building Standards Agency provides
guidance on complying in Scotland through a
new system of technical handbooks Section 6deals with energy use.
In Northern Ireland, The Building Regulations
Unit of the Department of Finance and
Personnel provides guidance via a series of
Technical Booklets Technical Booklet F deals
with energy use.
These building regulations place minimum standards,
i.e. they control elements, fixtures and fittings which are
being worked on, added or replaced. Table 1.1 provides
guidance upon what is controlled when working on
existing housing.
You are advised to check with the area building control
team whether or not your proposal requires approval
under the regulations.
Every building should be designed and constructed in a
way that conserves energy, and reduces carbon dioxide(CO2) emissions.
The advice contained within this guide provides
examples and specifications for the following scenarios:
Full refurbishment.
Works on individual elements.
Home conversions and the issues surrounding the
improvement of historic buildings are not explicitly
covered within this guide. For assistance on these
situations please see the Further information section at
the back of this guide.
The following sections cover works to existing housing
and what standards need to be achieved.
1.1 Minimum standards
Anyone carrying out building work on an item of a
property controlled by building regulations is required
by law to assess its performance with regards to the
conservation of fuel and power.
This involves ascertaining if the controlled item, for
example an external wall, meets the requirementsof building regulations, and then when required,
carrying out energy efficiency improvements (such
as the addition of insulation) where this is technically,
functionally and economically feasible.
Please note that complying with the building regulations is a separate matter from obtaining planning
permission for work to be undertaken.
Table 1.1 What items are controlled?
When working on, adding or replacing any of the following items you must check building regulation
requirements, and should also consider specifying to Energy Saving Trust best practice standards.
Controlled itemMinimum legislative
requirements?
Opportunity to specify
Energy Saving Trust
best practice?
Home conversions (e.g. garage and loft conversions). Yes Yes
Home extensions. Yes Yes
Building fabric (e.g. walls, roofs and floors). Yes Yes
Replacement openings (windows, doors or rooflights). Yes Yes
Heating systems and their control and distribution systems. Yes Yes
Other building services (e.g. lighting) Varies across the UK Yes
Items not controlled by building regulations include items such as landscaping. Emergency repairs, for example
a leaking hot water cylinder, may also be undertaken without delay.
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4 Energy-efficient refurbishment of existing housing (2007 edition)
1.2 Energy Saving Trusts best practice
standardsHome energy use is responsible for over a quarter of
UK CO2emissions which contribute to climate change.
To help mitigate the effects of climate change, the
Energy Saving Trust has a range of technical solutions
to help UK housing professionals build to higher levels
of energy efficiency.
This guide outlines the Energy Saving Trusts best
standards for refurbishment. Implementing these
recommendations will result in refurbished housing
being more energy efficient reducing CO2emissions
and saving energy, money and the environment.
Energy efficiency has a vital role in reducing fuel
consumption and making warmth affordable.
Houses undergoing major refurbishment now
are unlikely to be refurbished again before 2050.
Current refurbishment work has a major part to
play in meeting the UKs long term emissions
reduction targets.
Going beyond the minimum standards of building
regulations, and adopting the Energy Saving Trusts
best practice standards wherever this is technically,
functionally and economically feasible can result indramatically improved levels of energy efficiency being
achieved. Opportunities for specifying best practice are
provided in Table 1.1.
This guide does not focus on the financial benefits of
different measures . However information on savings
is contained with in the Energy Saving Trust guide
Domestic energy efficiency primer (CE101/GPG171),
see Further information for more guidance.
1.3 Demolition or refurbishment?
Britain has the oldest housing stock in the developedworld with 8.5 million properties over 60 years old and
whilst there is much talk about the house of the future,
at current demolition rates, the average house will have
to last for 1000 years before it is replaced. It is vital
therefore that we make improving the environmental
performance of our old housing stock a priority.
One of the problems that local authorities, regional
development agencies and private developers face
when choosing whether to refurbish or rebuild, is that
the issues they need to consider are broad ranging
and complex. Restoring or demolishing the UKsconsiderable housing stock poses decision-makers
with a range of technical, economic, environmental and
social issues to grapple with.
One of the tools which can be used to answer these
questions is EcoHomes XB. Developed in collaboration
with the Housing Corporation, it assists landlords
such as housing associations and local authorities in
planning and measuring the benefit of improvement
works to their housing stock and aiding overall
environmental performance.
Where the refurbishment of existing housing is inviable,the Energy Saving Trusts specification should be
adopted as a minimum for any potential new-builds.
This holistic approach achieves a 25 per cent reduction
in CO2emissions using established, cost-effective
products and practices. For assistance on achieving
the Energy Saving Trust specifications please see the
Further information section at the back of this guide.
1.3.1 Specifications and tenders
The cost of energy efficient construction can be kept to
a minimum by:
Ensuring that an integrated package of energy
efficiency measures is specified.
Including required energy efficiency measures
in the standard tender specification rather than
having them priced as extras.
Assessing the costs and benefits of each energy-
saving feature prior to tendering by carrying out
energy rating assessments.
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2 Best practice summary
For whole house refurbishment or the replacement
of individual components. Where refurbishment hasbeen identified as an appropriate solution the Energy
Saving Trust recommendations can be adopted. These
measures improve the energy efficiency and reduce
the CO2emissions of housing.
In housing refurbishment, it is impossible to prescribe
a single package of measures applicable to allexisting dwellings. However, a range of suitable, cost-
effective options are detailed in Table 2.1 [below]. The
specification adopted will depend, to a large degree,
on the proposed improvements and the form of
construction.
Area Improvement See page
1 Walls Where possible, walls should be insulated to achieve a maximum U-value of 0.30W/m2K 11
2 Roofs For best practice, aim for a U-value of 0.16W/m2K when installing insulation between the joists or rafters. Flat
roofs should be insulated to achieve a U-value of 0.25W/m2K or better.16
3 Floors Exposed floors should be insulated to achieve a maximum U-value of 0.20-0.25W/m2K (depending upon
floor geometry).
4 Windows Replacement windows should have a BFRC rating in band C or above. Any retained windows should be
draught-stripped.18
5 Doors Replacement doors should have a maximum U-value of 1.0W/m2K if solid, or 1.5W/m2K if half-glazed. Allexisting doors should be draught-stripped.
18
6 Space
heating and hot
water
Domestic wet central heating systems and hot water should be installed to meet Central Heating System
Specifications (CHeSS) Year 2005 standard HR6 or HC6. Where electricity is the only option, the
recommendations contained within Domestic heating by electricity (CE185/GPG345) should be followed.
23
7 Airtightness Air leakage paths can be identified using a pressure test and removed by undertaking remedial sealing. The
best practice recommendation is to aim for an air permeability of 5m3/(h.m2) at 50Pa.21
8 Ventilation A purpose-provided ventilation system should be installed. 19
9Lights and
appliances
When re-wiring dedicated lamp fittings should be installed which accept only low-energy bulbs. Ideally
greater than 75 per cent of all fixed luminaries should be dedicated low energy fittings. Low energy
appliances should be specified which carry the Energy Saving Recommended certification mark.
27
10 Renewable
and low-carbontechnologies
After all basic energy efficiency improvements have been undertaken the specification of renewable
technologies, such as solar hot water heating or photovoltaics, is encouraged where appropriate to furtherreduce environmental impact. 30
Table 2.1 Recommended improvements
Walls
Roofs
Floors
Windows
Doors
Space heating and hot water
Airtightness
Ventilation
Lights and appliances
Renewable and low-carbon technologies
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Energy-efficient refurbishment of existing housing (2007 edition) 7
For an interactive guide please visit
www.energysavingtrust.org.uk/housing. Energyefficiency improvements can also be combined with
virtually all repairs they need not wait for a full
Table 2.2 Opportunities to include energy efficiency in repair and improvement work
Improvement
Opportunity
Internalwallinsulation
Highperformancedoorsand
windows
Cavitywallinsulation
Externalwallinsulation
Ventilation
Draught-stripping
Insulateloft
Insulatewaterpipes
Ventilateloftspace
Insulatefloors
Addporch
Low-energylighting
Insulatehotwatercylinder
Improvecontrols
A-ratedboiler
Sustainableenergysources
Refitting kitchens and bathrooms 3 3 3 3 3 3 3 3 3
Repointing of walls 3
Repairing walls or render upgrading
external appearance 3 3
Replastering 3
Replacing wall ties 3
Rewiring 3 3 3 3 3
Replacing windows and doors 3 3 3
Repairing cladding 3
Re-roofing / roof repairs 3 3 3 3
Repairing ground floors 3 3 3
Repairing heating and plumbing 3 3 3 3 3 3
Increasing security 3 3 3
refurbishment of the building. It is always cheaper to
combine them, rather than install them separately.Some of these opportunities are shown in Table 2.2.
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8 Energy-efficient refurbishment of existing housing (2007 edition)
2.1 Consulting residents
Occupants should be involved in the decisions thataffect their homes. This can be done in a number of
ways:
Meetings and discussions with residents groups.
Surveys and questionnaires.
Home visits.
A general consultation policy (particularly if there
are no allocated or existing occupants).
Caretakers and estate management staff should also
be involved in the decision-making process.
To help occupants feel involved, landlords and private
developers should:
Discuss proposals with them at an early stage and
be open about the issues.
Provide all available information to allow occupants
to make an informed choice.
Listen to occupants views and act on them if
possible.
Allow enough time for consultation.
2.2 Benefits to the landlord
It is more cost-effective to incorporate energy efficiency
measures into planned improvement or repair
work than to react on an ad hoc basis to individual
problems.
The insulation packages recommended in this
document will reduce or eliminate condensation and
mould growth, often a significant source of both ad
hoc repair work and overall maintenance costs.
Energy advice
The following suggestions may be helpful in
creating an energy advice programme enabling
occupants to make effective use of their heating
and ventilation systems.
Following refurbishment, give occupants a
specially-written leaflet on how to run their
homes in an energy efficient way.
Ensure that face-to-face advice is given by a
trained representative.
Offer special training to a resident who can
act as a local energy advisor.Check the setting on each system and
provide energy advice to occupants as part
of the first year defects inspection.
Monitor fuel bills (with residents agreement)
and advise occupants on how to reduce
them.
Give advice on energy efficient lighting
including the long-term benefits of investing
in the more expensive CFLs.
Provide a durable information sheet, and fix
it in a convenient location where it will beread.
For more information on giving good energy
advice see the Energy Advice Handbook
referenced within the Further information section
at the back of this guide.
Any organisation giving energy efficiency advice
(or who contract out this service to a third party)
should sign up to the Domestic Energy Efficiency
Advice Code of Practice, which is run by the
Energy Saving Trust. The Code of Practice hasbeen developed to ensure consumers receive
accurate and relevant energy efficiency advice
and information.
For further details visit:
www.goodenergyadvice.org.uk or
call the helpline: 020 7222 0101
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3 Best practice measures: Insulation standards
This section looks at ways of insulating the most
common forms of construction. Best practice for eachsolution is highlighted.
All exposed (and semi-exposed) elements of the
dwelling should be insulated to the best possible
standard. This will minimise heat loss in the most
cost-effective way and reduce thermal bridges.
Wherever possible insulation works should take place
ahead of heating upgrades in order to reduce heating
demand and improve comfort. For insulation, the
minimum thermal resistance (R) required is often
specified instead of a U-value. The thermal resistance is
calculated by
R = L/m
where Ris the required thermal resistance of the
insulation in m2K/W, Lis the thickness of the material
in metres and mis the thermal conductivity of the
insulation in W/mK. To compare two insulants of
different thickness and thermal conductivity, the
R-value is calculated. The one with the higher value
has the better thermal performance. If the required
R-value is known, the necessary thickness of a specificinsulation material can be calculated.
3.1 New or replacement elements
When undertaking alterations to a dwelling (e.g.
replacement of an external wall) or the addition of an
extension, to achieve best practice the specifications
adopted should be as those for new dwellings as far
as practically possible.
Table 4 Summary of recommended insulation standards
Existing
construction
element
Typical
U-value
W/m2.K
Improvement measure
Target
U-value
W/m2.K
Cavity walls 1.5
Fill cavity with insulation. It is highly recommended to consider adding
additional external or internal insulation to achieve improved levels of
performance.
0.5 to 0.6
Solid walls 2.1
Insulate internally using insulation backed dry-lining, insulation with studwork,
or insulate externally using wet render, dry cladding or bespoke systems.
Between 80 to 140mm of insulation will be required in all cases to achieve the
target U-value (dependant upon insulant conductivity).
0.30
Floor 0.70 Insulate above or below concrete slab, or between joists of timber groundfloor with between 100 to 200mm of insulation (depending upon geometry). 0.20 to 0.25
Pitched roof
(uninsulated)1.9
Install 250 to 300mm mineral wool quilt (first layer between joists, second
layer across joists).0.16
Insulate between rafters with insulation in addition to 40 to 100mm of
insulation either above or below the rafters (dependant upon insulant
conductivity).
0.20
Flat roof 1.5Add 100 to 160mm of insulation above structural deck (dependant upon
insulant conductivity). If replacing a pitched roof should be considered.0.25
Glazing 3.1Replace with high performance windows that incorporate integral draught-
stripping.
BFRC rating in
band C or better
Further information
For assistance on achieving the Energy Saving Trust best practicerecommendations please see the Further reading section at the back
of this guide. For more detailed guidance on insulation please see
the following Energy Saving Trust literature:
Insulation materials chart: thermal properties and environmental
ratings (CE71).
Effective use of insulation in dwellings (CE23).
Practical refurbishment of solid-walled housing (CE184).
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3.2 Thermal bridging
Thermal bridging is common in older buildings. Evenwith a high standard of retrofitted insulation, cold spots
can occur on internal walls leading to discomfort and
condensation. Particular care should be taken where:
Internal insulation is used.
The concrete frame, floor slabs or edge beams are
exposed.
The details shown in Figures 3.1 to 3.4 representpractical ways in which thermal bridging can be
reduced, best practice is to eliminate the bridge
completely. However in some situations this is not
feasible, in which case the minimum recommendations
are shown.
Insulation (a)
Joist
Insulation (b)
Floor
Figure 3.1 Timber ground floor junction
Best practice
Specify floor insulation as well as dry-lining
to minimise thermal bridging (a).AND
Insulate between the last joist and the wall (b).
Note: Internal insulation should include vapour check on
the warm side of the insulation.
Floor insulation
Figure 3.2 Concrete ground floor junction
Best practice
Butt the floor insulation up against the dry-lining
to avoid thermal bridging.
Note: This detail may be impractical if height
adjustments to doors and staircases cannot be made.
Figure 3.3 Exposed concrete floor (e.g. above driveway or garage)
Insulation (a)
Insulation (b)
Minimum recommendations
Insulate edge of ring beam (a).
Insulate underside of exposed concrete (b).
Figure 3.4 Steel lintel junction
Insulation
Minimum recommendations
Add insulation to soffit and reveals.
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Insulation standards
3.3 Cavity walls
Unfilled cavity walls can be filled at any time, withheat loss through the walls being reduced by up to
60 per cent. The typical installed cost of cavity wall
insulation is around 500, with payback usually
occurring in around two years.
3.3.1 Description
Installing cavity wall insulation is a specialist job
and must be carried out by a suitably qualified
contractor: See the Energy Saving Trust publications
listed in the Further information section.
A CIGA (Cavity Insulation Guarantee Agency)guarantee should also be provided (excludes non-
traditional structures).
3.3.2 Suitability of cavity walls
Most masonry cavity walls can be filled with
insulation, especially those beneath 12 metres
in height built after 1930. In fact, there are
systems available for buildings up to 25 metres
in height and a few even taller buildings have
been successfully cavity-filled, following special
assessment.
Almost all of the systems on the market areapproved for use in all parts of the UK. However,
this assumes that the outer leaf is constructed
in accordance with the requirements for local
exposure conditions so that water penetration of
the outer leaf is minimal.
The exception is urea formaldehyde foam, which
is subject to restrictions in parts of the country and
some forms of construction. BS 5617 and BS 5618
provide further information (please see the
publications section at the back of this guide).
Where cavity walls are not suitable for cavity
insulation they can be treated as solid walls.
Insulationis blowninto thecavity
Insulationinjected
through
holes inouter leaf
Figure 3.5 Insulation injected into cavity
Air bricks and balanced flues should
be sleeved.
Polystyrene should not be used if
there are any unprotected PVC cables
in the cavity, or if there are PVC cavity
trays or damp proof courses (dpcs).
Air ventilators crossing the cavity
should be sleeved (or sealed if
obsolete).
Standard for cavity walls
Best practice for cavity walls is to have them filled with insulation. If the
internal surface is being replaced an insulation backed plasterboard should be
considered to further improve the thermal performance. It is considered best
practice to insulate cavity walls when undertaking any of the following activities:
Re-plastering or dry-lining of internal surfaces.
Re-pointing.
Rendering externally.
When undertaking a home conversion or adding a conservatory.
Replacing the heating system (as insulation may allow a smaller, and
potentially cheaper system to be specified).
Further Information
For more detailed guidance on cavity wall insulation please see Cavity wall
insulation in existing dwellings: a guide for specifiers and advisors (CE252)
3.4 Solid walls
Solid walls can be insulated internally or externally.
A conventional 220mm solid brick wall with internal
plaster will have a U-value of 2.1W/m2K. Insulating a
solid wall to best practice will save around 300 a year
on heating costs.
Standard for solid walls
Applying an insulation with an R-value of
2.9m2K/W will improve the walls U-value to
0.30W/m2K. This will require between 80 to
140mm of insulation (dependant upon the
insulants conductivity).
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3.5 Internal wall insulation
It is most cost effective to include internal wallinsulation in a full refurbishment or modernisation
scheme. It is a false economy to install new plumbing,
wiring and a central heating system without insulating
the dwelling at the same time.
The main types of internal insulation system are:
Directly applied insulation.
Internal insulation with studwork.
In both approaches, the number of penetrations
through the insulation layer should be kept to aminimum to reduce air leakage.
Figure 3.7 shows a combined layer of a rigid insulation
board and insulation-backed plasterboard to achieve
a very high level of thermal performance around a
window bay.
Figure 3.6 Internal wall insulation
Further Information
For more detailed guidance on internal wall
insulation please see Practical refurbishment of
solid-walled houses (CE184).
Figure 3.7 Insulation around window bay
Assess the condensation risk in accordance with
BS 5250 (2002).
Apply a rough skim of mortar down to skirting
level, and up to ceiling level on any perimeter
walls and seal around any penetrations throughthe wall to reduce air leakage.
Install mechanical fixings in accordance with the
manufacturers recommendations.
Insulation should be returned into the reveals
and soffits of window and door openings.
PVC-sheathed electrical cables should not come
into contact with polystyrene insulation as this
can degrade the integrity of the cable insulation.
Return the insulated dry-lining a short distance
along separating walls, floors and ceilings toavoid condensation at the thermal bridge.
3.5.1 Suitability of internal insulation
Cheaper than external insulation.
External wall appearance is maintained.
Internal wall surface warms up more quickly.
Easier to install and maintain than external
cladding.
Can leave thermal bridges.
Fixing of heavy items can be difficult.
Reduced room size can be critical in small
dwellings.
Skirting boards, cornices, door frames and electrical
fittings need repositioning.
Can be disruptive to occupants.
Vapour controllayer
Insulation between studworkor insulation backed plasterboard
Insulation withminimumR-value2.9m2/KW
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Insulation standards
3.6 External wall insulation
External insulation is generally the more expensiveway to insulate. However for constructions that require
periodic re-rendering such as no-fines concrete, or
where extensive remedial action is needed (to combat
rain penetration, for example), then the extra cost of
additional insulation is relatively low.
The design and installation of external wall insulation
systems is a specialist job. Use an insulation system
with current approvals certificates for all components.
The main types of external insulation system are:
Wet render systems.
Dry cladding systems.
As insulation and fixing components are common
to most wet render systems, performance generally
depends on the thickness of insulation and quality of
the render.
Dry cladding is particularly suitable where fixings can
only be used on particular areas of the building. In
addition, these systems permit access for periodic
checks or maintenance work, as is often required with
high-rise buildings. Dry cladding is rarely used on low-rise dwellings as the cost is prohibitive.
3.6.1 Suitability of external wall insulation
Can be applied while occupants remain in
residence.
Thermal bridging is avoided, except in the case of
projections such as balconies.
Can change external appearance dramatically.
Can be used to revitalise and modernise a property
and so extend its life.
Can be cost effective where the external walls
require remediation.
May be vulnerable to impact damage.
Vulnerable areas need protection.
Rainwater goods and sills usually require work.
Further Information
For more detailed guidance on internal wall insulation please see External insulation systems for walls of
dwellings (CE118/GPG293).
Figure 3.8 External insulation
Confirm with installer acceptable details at the junction of the wall
insulation with roof eaves and verges, window and door openings,
and other features.
If a combustible insulant is used, consult the approvals certificate for
necessary precautions.
Check if planning permission is needed where the external
appearance is to change.
No-fineswall
Render (or other finish)
Insulation with minimum R-value2.3m2K/W fixed to wall withadhesive and mechanical fixings
Figure 3.9 Example of a refurbished high-rise building
Moorfield, by Bristol City Council
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3.7 Floors
Heat loss through exposed floors depends on: thesize and shape; the type of floor; and the conductivity
of the ground below it. Heat loss is greatest around
the edges of the floor, so shape is important. Losses
would differ between, say, a mid-terrace and an end-
terrace dwelling. Specifying a common U-value for
both would result in different insulation thicknesses
and finished floor levels. This is not practical. It is
easier to specify an R-value than a U-value.
Heat loss through floors can be reduced by up to
60 per cent by adding insulation, with an annual
saving of around 45.
3.7.1 Solid concrete floors
Where the floor is being retained the only simple
option is to install insulation and a new deck on top.
However care needs to be taken, particularly at stairsand door thresholds. A 60mm layer of phenolic,
polyisocyanurate or polyurethane foam insulants can
achieve best practice.
Where the screed or ground floor slab is being
replaced there is an opportunity to incorporate
insulation. The finished floor level should coincide with
the previous level if possible in order to avoid unequal
or excessive step heights at doors or staircases.
Insulation can be added above or below the slab.
3.7.2 Suitability
Insulation above the slab If the insulation is placedabove the slab, the room will warm up more quickly
when the heating is switched on. The damp proof
membrane should be placed above the concrete slab.
Moisture-resistant flooring grade chipboard should be
used, with room for expansion around the edges.
Insulation below the slab This is the preferred option in
a warm south-facing room. The concrete slab on top
helps absorb heat and limits overheating. An up-stand
of insulation (R-value of 0.75m2K/W) the same height
as the slab should be put around the perimeter of the
room. Joints between the insulation boards shouldbe taped with water-resistant tape to stop concrete
seepage.
Screed
25mm edge insulation
Damp-proof membrane
Rigid water-resistant insulation withR-value greater than 2.5m2K/W
Figure 3.11 Concrete ground-bearing slab with Insulation below slab
Flooring grade chipboard orplywood
Rigid insulation with R-value greaterthan 2.5m2K/W
Damp-proof membrane
Minimum 10mm gap for expansion
Figure 3.10 Concrete ground-bearing slab with insulation above slab
Standard
Solid floor: R-value of 2.5m2K/W.
Timber suspended floor: R-value of
3.75m2K/W.
This will generally achieve a U-value between
0.20 to 0.25W/m2K
The surface below the insulation should be both smooth and flat to a
tolerance of 5mm in 3m (power-trowelled or levelled with screed).
This construction requires waterproof insulation with sufficient
compressive strength.
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Insulation standards
3.7.2 Suspended timber floors
Insulation should fully fill the space between the joistsand be the full depth of the joist. If there is a cellar or
basement, insulation can easily be installed from below
(see Figure 3.12). Building control should be consulted
to ensure correct fire performance is achieved. Mineral
wool or rigid insulating boards can be used. The
insulation should be placed tight up to the underside
of the floor but not be over-compressed.
New floor deck
Mineral fibre quilt or blown-ininsulation fully filling floor void
Support netting
Figure 3.13 Suspended timber ground floors, access from above
Figure 3.12 Suspended timber ground floors, access from below
Seal against draughts
Existing flooring
Mineral fibre quilt or blown-ininsulation fully filling floor void
Support netting stapled to joist
Pushing insulating quilt into gapbetween last joist and wall
Rigid insulation with R-valuegreater than 3.75m2K/Wsecured by battens
Skirting boardremoved
Existingfloorboards lifted
to offer access
Insulate gap
betweenlast joistand wall
Insulationbetween
joists
Supportingnettingdrapedandstapled tojoists tosupportinsulation
Insulationbetween
joists
Projectingnails or clips
to prevent
boardslipping
Insulategapbetween
last joistand wall
Existingfloorboards
Floor may need a fire resistance of up to an hour if over the basement.
Draught-stripping of floor at skirting.
Do not specify a vapour-control layer it can trap spilt water.Ensure the under-floor void is well ventilated.
Further Information For more detailed guidance on internal wall insulation please see Practical refurbishment of solid-walledhouses (CE184)
Where there is no access from below, the only
practical way to insulate the floor is by taking upthe floorboards (see Figure 3.13). Timber suspended
floors can suffer with draughts from between the
floorboards, around radiator pipes and under the
skirting boards. These need to be sealed. Membranes,
expanding foam and mastic all have a role to play
here. All timbers should be inspected for damp, rot or
infestation prior to the addition of insulation.
Specify draught-stripping of floor at skirting.
Do not specify a vapour-control layer it can trap spilt water.Ensure the under-floor void is well ventilated.
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Insulation standards
Energy-efficient refurbishment of existing housing (2007 edition)
3.8 Roofs
Lofts are the easiest to insulate either insulatingbetween the joists, or at roof level in the rafters. Attic
rooms and flat roofs can be insulated, but the work is
best done during a conversion or major renovation.
Loft insulation usually costs from around 500 with
the payback occurring after two years if the loft was
previously uninsulated.
3.8.1 Pitched roofs
Pitched roofs can be insulated at the ceiling level,
between the joists, or between the rafters (where
there is an existing attic room or a new room in the
roof). In all roof constructions, interstitial condensation
should be avoided. The location of services and how
these run in relation to the roof insulation layer must
also be given due consideration.
Seal any holes around services, especially those
from kitchens, bathrooms and airing cupboards.
Keep electrical cables above the insulation to avoidoverheating.
Avoid placing tanks and pipes in the roof if
possible (low mains water pressure may not make
this possible).
Any pipes or tanks located in the roof space must
be adequately insulated.
Eaves ventilator ensures
correct gap is maintainedin roof structure
Airtightenclosure forrecessed light
Insulationbetween andabove joists
Low vapour resistanceunderlay belowcounter battens
0.16W/m2K
Counter battens nailed through insulation
Plasterboardwith vapourcontrol layer
Insulation betweenand above rafters
Mineral wool (or similar) packedinto eaves to increase air tightnessTimber stop
for insulationabove rafters
Standard
For best practice, aim for a U-value of
0.16W/m2K when installing insulation between
the joists or rafters (for rooms in the roof anystud walls and dormer cheeks should aim to
achieve a U-value of 0.3W/m2K or better).
Sometimes achieving best practice U-values may
require large insulation thicknesses (for example
over 60mm below rafters). This may reduce
internal space and headroom. In these restricted
situations, it may be more practical to aim for
a U-value of 0.20W/m2K. Flat roofs should be
insulated to achieve a U-value of 0.25W/m2K or
better.
Figure 3.14 Best practice for roof insulation at ceiling level between and over joists
Figure 3.16 Best practice for roof insulation between and above the rafters
50mm airspace forcross ventilation
Stud walls and dormer cheeksto achieve U-value of 0.30W/m2K
0.16W/m2K
0.16W/m2K
Figure 3.15 Best practice for roof insulation between and below the rafters
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Insulation standards
3.8.2 Flat roofs
The preferred method of insulating a flat roofis to locate the insulation above the roof deck.
The insulation can either be placed below the
weatherproof membrane in a warm roof deck
construction, or above the waterproof membrane in
an inverted warm deck. It is most economical to add
insulation when replacing the roof covering.
Warm deck construction
Insulation boards to be rigid.
Insulation materials must be compatible with any
bonding materials used for the weatherproofmembrane.
Voids in timber roof must not be ventilated to the
outside.
Inverted warm deck construction
The existing roof structure must be capable of
supporting the extra weight, particularly of the
ballast layer
U-value: 0.25W/m2K
Timber or concrete deck
Weatherproof membrane
Rigid insulation with R-valuegreater than 3.7m2K/W
Weatherproof membrane
Timber or concrete deck
Weatherproof membrane
Rigid insulation with R-valuegreater than 4.4m2K/W
Ballast layer to holddown insulation
U-value: 0.25W/m2K
Further informationFor more detailed guidance on roof insulation
please see the following Energy Saving Trust
literature:
Practical refurbishment of solid-walled
houses (CE184).
Energy efficient loft conversions (CE120).
Figure 3.17 Warm deck construction
Figure 3.18 Inverted warm deck construction
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Insulation standards
Energy-efficient refurbishment of existing housing (2007 edition)
3.9 Windows and doors
The replacement of windows and doors can havea significant impact on heat loss from a dwelling.
The greatest impact comes through the reduction of
infiltration heat losses from minimising draughts.
Replacement windows should always be fitted by a
reputable installer and sealed around the frame (to
reduce draughts and air leakage at the wall-to-frame
junction). In England and Wales, a FENSA registered
installer should be used (please see Relevant
organisations and websites).
Replacement of windows in historically sensitive
buildings should only be undertaken after consultation
with the local authoritys building conservation officer.
Secondary glazing is a good option where thermalperformance needs to be improved and the existing
character of the dwelling needs to be maintained.
Draught-stripping of existing badly fitting windows and
doors is inexpensive and simple to install. It can greatly
improve comfort as well as reducing heat loss.
Table 5 Best practice for replacement windows
Frame typeGlass
layersGlass type
Air
gap
(mm)
Gas fill SpacerBFRC
RatingBand U-value
Bestpractice PVC-U (5 chamber) 3
2 x low iron
1 x hard coat16 x 2 Argon Warm edge hybrid +4 A 1.3
PVC-U (5 chamber) 2 soft coat 16 Argon Silicone rubber -8 B 1.4
PVC-U (3 chamber) 2 soft coat 16 Argon Silicone rubber -13 C 1.5
Timber 2 soft coat 16 Argon Corrugated metal strip -16 C 1.5
PVC-U (5 chamber) 2 soft coat 16 Argon Hard polyurethane -18 C 1.6
Timber 2 soft coat 16 Air Silicone rubber -22 D 1.6
PVC-U (5 chamber) 2 soft coat 16 Argon Aluminium -23 D 1.6
Aluminium (23mm polyamide breaks) 2 soft coat 16 Argon Silicone rubber -26 D 1.8
Timber 2 hard coat 16 Air Silicone rubber -27 D 1.8
Best practice
Windows with a British Fenestration Rating Council
(BFRC) Rating in band C or better
Solid insulated door: Maximum U-value of
1.0W/m2K
Half-glazed insulated door: Maximum U-value of
1.5W/m2K
Further informationFor more detailed guidance on windows and
doors please see the following Energy Saving
Trust literature:
Windows for new and existing houses
(CE66).
Energy efficient historic homes case studies
(CE138).
A windows thermal performance depends
on a number of factors including: design,
the materials used and the combination of
components.
The BFRC has developed a system for
comparing the overall energy performance of
windows. More information can be found at:
www.bfrc.org
The rating system is based
on the total annual energy
flow through the window
(kWh/m2/yr).
The ratings are grouped
into bands from A-G. It is
anticipated that the BFRC
Rating will eventually
replace U-values as the
main UK method for
specifying windows.
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Purpose-provided ventilation (e.g. ventilators and
windows) and extract fans are required to replacestale indoor air with fresh outdoor air.
Adequate venti lation is needed for both the comfort
and the safety of occupants, as it removes or dilutes
pollutants that accumulate in the dwelling.
Once the dwelling is sufficiently airtight, controlled
ventilation can be installed. The main systems are
described briefly below.
Relevant national standards and regulations should
be followed.
4.1 Natural background ventilators
Background ventilators are required in order to
provide a minimum supply of fresh air for occupants
and to disperse residual water vapour. Background
ventilators provide continuous ventilation
throughout the dwelling.
These are an essential part of most ventilation
strategies as they provide the minimum failsafe
background ventilation for all types of systems.
This is not the type of ventilator specified forcombustion devices in UK building regulations,
which must remain permanently open . The BRE
information paper Background ventilators for
dwellings (see Further information section) gives full
details of each different type.
4.2 Passive stack ventilation (PSV)
The layout of existing dwellings usually makes
passive stack ventilation difficult to incorporate.
However, adequate levels of ventilation can be
achieved by this method.
PSV is a system of vertical or near-vertical ducts that
run from the kitchen and bathroom to vents on
the roof. Moist air is extracted by the stack effect
warm air is less dense and so rises and by the
effect of wind flows over the roof. Extract grilles
with humidity control should be specified. Fresh
air entering the dwelling should be controlled with
trickle vents (preferably also with humidity control ).
The most obvious energy saving feature of PSV
systems is that they consume no electricity.
However, they do exhaust heat energy.
4.3 Local extract fans
Extract fans remove stale or polluted air from kitchensand bathrooms, while fresh air is drawn into the
building via background ventilators in other rooms.
Building regulations in each part of the UK give the
required extract rates for fans.
Low power extract fans using DC motors are now
readily available, saving up to 80 per cent of the
electricity required by conventional units. Ideally, all
extract fans should have a humidistat controller to keep
the room humidity at an acceptable level, normally
below 70 per cent relative humidity.
For effective ventilation, extract fans should be located:
As high as possible in the room.
Close to the source of the pollution.
As far as possible from the source of fresh air.
In accordance with manufacturers
recommendations.
Passive infra-red (PIR) detectors (built-in or remote) can
be used to activate this type of fan. Usage detection
controls can turn on extract systems when a specific
appliance, for example a shower, is used.
If occupants are made aware of the importance and
low running costs of local extract fans, there is less
likelihood they will disable them.
Stack ducts
4 Energy Saving Trust technical recommendationsVentilation
Figure 4.1 Passive stack ventilation
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Ventilation
Energy-efficient refurbishment of existing housing (2007 edition)
4.3 Single room heat recovery ventilators
(SRHRVs)The single room heat recovery ventilator is a development
of the extract fan which incorporates a heat exchanger. It
recovers 60 per cent or more of the heat in the outgoing air.
This can then be used to preheat incoming air.
The supply and extract fans are often dual speed, providing
low-speed continuous trickle intake, and high-speed boost
extract. The higher speed setting can be controlled manually,
via a humidistat or usage detection control system.
The design considerations regarding location are similar to
those for extract fans.
4.4 Mechanical extract ventilation (MEV)
An MEV system continually extracts air from wet rooms
such as kitchens and bathrooms.
It usually consists of a central ventilation unit positioned
in a cupboard or loft space, ducted through the dwelling
to extract air from the wet rooms. The supply air needs to
be controlled and the inlet vents need to be positioned
where they will not cause discomfort. Passive vents may be
appropriate.
To qualify as best practice standard, the whole system musthave a specific fan power of 0.6W/l/s or less when tested in
the appropriate configuration via SAP Appendix Q. Further
information on SAP Appendix Q, the test methodologies
and test results of eligible systems can be found at www.
sap-appendixq.org.uk
4.5 Whole house mechanical ventilation with heat
recovery
These systems deliver the required ventilation rate almost
independently of weather conditions. However, the energy
saving benefits will only be realised in airtight properties.
Therefore this type of system should only be used inproperties with an airtightness better than 5m3/(h.m2) at
50Pa pressure.
The good practice standard is met by following the relevant
national standards and regulations. To qualify as best
practice standard, the whole system must have:
A specific fan power of 1W/l/s or less
A heat recovery efficiency of 85 per cent or higher
Both when tested in the appropriate configuration via SAP
Appendix Q. Further information on SAP Appendix Q, the
test methodologies and test results of eligible systems can
be found at www.sap-appendixq.org.uk
Supply andextractsystem
Figure 4.3 Whole house mechanical ventilation
with heat recovery
Further information
For more detailed guidance on ventilation
please see the Energy efficient ventilation
in dwellings (CE124/GPG268).
Figure 4.2 Mechanical extract ventilation (MEV)
Extract system
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Energy-efficient refurbishment of existing housing (2007 edition) 21
A ventilation and airtightness strategy should be
part of any refurbishment works. The objective is toprovide a balance between energy efficiency and
indoor air quality.
Air leakage is the infiltration of air via unwanted gaps
and cracks in the building envelope.
Too much air leakage leads to heat loss as well as
discomfort from cold draughts. The principal air
leakage pathways are illustrated in Figure 5.1. As
thermal insulation standards improve the proportion
of total heat lost via infiltration increases significantly.
As a part of any major refurbishment works air
leakage paths should be identified and minimised.
A pressure test may be used to identify air leakage
pathways suitable for remediation works.
The potential to improve airtightness of a dwelling
will depend on the nature of the existing building and
the type of works being undertaken. It is therefore
difficult to set absolute targets but the best practice
recommendation is to aim for an air permeability of
5m3/(h.m2) @ 50Pa.
The results of an airtightness test can be used to:
Assess the airtightness of the dwelling against
recognised standards.
Identify air leakage paths and the rate of air
leakage.
Assess the potential for reducing air leakage in
the dwelling.
Measure improvements achieved by remediation
work.
Please note that care must be taken when dealingwith historic buildings.
5 Energy Saving Trust technical recommendations Airtightness
1
2
3
4
5
6
7
8
16
9
10
11
12
13
14
15
Most common air leakage paths
1 Underfloor ventilator grilles.
2 Gaps in and around suspended timber floors.
3 Leaky windows or doors.
4 Pathways through floor/ceiling voids into cavity walls and then to the
outside.
5 Gaps around windows.
6 Gaps at the ceiling-to-wall joint at the eaves.
7 Open chimneys.
8 Gaps around loft hatches.
9 Service penetrations through ceilings.
10 Vents penetrating the ceiling/roof.
11 Bathroom wall vent or extract fan.
12 Gaps around bathroom waste pipes.
13 Kitchen wall vent or extractor fan.
14 Gaps around kitchen waste pipes.
15 Gaps around floor-to-wall joints (particularly with timber frame).
16 Gaps in and around electrical fittings in hollow walls.
Figure 5.1 The most common air leakage paths.
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Airtightness
Energy-efficient refurbishment of existing housing (2007 edition)
5.1 Disadvantages of draughty dwellings
CO2
There will be higher emissions.
Space heating
Excessive heat loss means that a correctly-sized heating
system may not be able to satisfy demand.
Comfort
Draughts and cold spots can cause discomfort.
Excessive air leakage may make rooms uncomfortably
cold. Draughty dwellings tend to give rise to
complaints from occupants.
Risk of deterioration
Damp air can penetrate the building fabric, degrading
the structure and reducing the effectiveness of the
insulation. Air leakage paths often produce unsightly
dust marks on carpets and wall coverings.
Table 5.1. How to improve airtightness in existing dwellings
Windows and doors Seal gaps around windows and doors to prevent air leakage via the reveals and
thresholds.
Apply an external mastic seal to all window and door frames.Seal any internal gaps where the wall reveals/window boards abut window units or
external doors with a bead of mastic.
Repair any damage to window frames and ensure the casements, sashes and top-
lights close firmly. It may be necessary to replace closing mechanisms.
Apply draught-stripping to gaps around window casements, sashes and top-lights.
Walls Air leakage behind dry-lining can be reduced by injecting continuous ribbons of
expanding polyurethane foam between the plasterboard sheets and the inner leaf
blockwork.
Make good damage to mortar joints and fill holes in external walls.
Floor Improve timber floors by laying hardboard sheeting over the top. Do not use plastic
sheeting to cover timber floors as this may cause the timber to rot.Seal around the edges of the room and make good any gaps around service pipes.
Roof Ensure the loft hatch fits snugly into its aperture and apply draught-stripping between
the hatch and the frame.
Services Seal gaps around any service pipes and cables passing through external walls, ceilings
and ground floors.
Further Information
For more detailed guidance on airtightness
and ventilation please see the following Energy
Saving Trust literature:
Improving air tightness in dwellings
(CE137/GPG224).
Energy efficient ventilation in dwellings
(CE124/GPG268).
Energy efficient historic homes case studies
(CE138).
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Space heating provides thermal comfort where and
when required. Heat gains from the sun, occupants,the hot water system, cooking and electrical appliances
supplement the main heating source.
An energy efficient heating system:
Is correctly sized to warm up the dwelling from
cold within a reasonable time (normally one hour).
Uses fuel as efficiently as possible.
Can be accurately controlled.
Has controls that are easy to use and understand.
An efficient system will have low running costs and
can increase the value of a property.
A complete system replacement provides the best
opportunity for improving energy efficiency. It also
allows a reassessment of fuel choice: this has a great
influence on the running costs and on the systems
environmental impact. A partial upgrade can give many
of the same benefits, particularly when controls and
insulation are improved or the boiler replaced.
6.1 Fuel choice
The choice of fuel depends on availability andaffects running costs and CO2emissions as shown
in Figure 6.1. Due to the significantly lower carbon
emissions natural gas, where available, is the preferred
fuel for wet heating systems.
Low High
Space and water heating running costs (/year)
kg CO2 per year
Space and water heating running costs and CO2emissions
Electricity
LPG
Processed smokelesssolid fuels
Wood pellet or chip*
Oil
Main gas
* Chipped or pelleted fuel is only available in a few areas and the price can vary considerably. At present there is no labelling scheme for woodpellets or chips. This means that without verification of the source, levels of emissions and air pollution cannot be guaranteed.
Low Highkg of CO2per year
Running costs (/year)
6 Energy Saving Trust technical recommendations Space heating and hot water
Figure 6.1 Space and water heating running costs and carbon dioxide emissions
The fuel prices and associated CO2emissions used
in the comparison are taken from SAP2005. Currentprices should be checked when selecting a fuel.
Electric resistance heating should only be used where
all insulation measures have been adopted.
6.2 Recommended upgrade package
The recommended heating upgrade packages are
the best practice specification set out in CHeSS (see
Table 6.1).
Systems need to be correctly sized. A number of
factors should be considered, particularly for newsystems in homes where the fabric insulation has been
upgraded:
Ventilation heat losses need to be addressed.
The size of the boiler will be determined by hot
water demand as well as space-heating needs.
The size of the new boiler should take insulation
improvements into account.
The system should be accurately controlled to its
design temperatures set out in BS 5449.
It is vital that occupants are consulted and advisedon how best to operate their new systems. For
more information on energy advice see the Energy
Advice Handbook in the Further information section
of this guide.
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Space heating and hot water
Energy-efficient refurbishment of existing housing (2007 edition)
6.3 Seasonal boiler efficiency
The SEDBUK (Seasonal Efficiency of Domestic Boilers inthe UK) rating is a measure of the efficiency of a boiler
installed in typical domestic conditions in the UK and is
used in the SAP. The efficiency of most boilers can be
found on the Governments boiler efficiency database
www.boilers.org.uk
6.4 Condensing boilers
The energy performance standard for new andreplacement boilers was raised in England and Wales
in April 2005, Northern Ireland in November 2006
and Scotland in May 2007. When replacing a boiler, a
condensing boiler (with a seasonal efficiency of greater
than 86 per cent) must now be installed in the majority
of cases.
6.5 Combination boilers (combi)
Combi boilers provide space heating and instant
mains-pressure hot water. They do not require header
or hot water storage tanks. The power of the boiler
is normally selected on the basis of the hot waterrequirement. Choosing between a combi and a
regular boiler is discussed in the Energy Saving Trust
publications CE29, CE30 and CE47.
Some instantaneous combi boilers have a keep hot
facility (sometimes called warm-start) which keeps
water within the boiler permanently hot to reduce
warm-up time at boiler start-up. The keep hot facility
must be timed to switch off overnight as its use may
increase running costs.
6.6 Radiators
Placing insulation with a reflective coating behindradiators on uninsulated external walls will increase
their effectiveness. However, improved wall
insulation gives greater benefit.
Table 6.1 CHeSS HR6 and HC6 specifications
Regular system (CHeSS HR6) Combi system (CHeSS HC6)
Description Domestic wet central heating system with
regular boiler and separate hot water store
Domestic wet central heating system with
combi or CPSU boiler.
Boiler SEDBUK Band A rating SEDBUK Band A rating (A or B for oil)Hot water store High-performance hot water cylinder, or
high performance thermal storage system
None, unless included within boiler
Controls Programmable room thermostat with
additional timing capacity for hot water
Programmable room thermostat
Cylinder thermostat N/A
Boiler interlock
TRVs except in the room with a room thermostat
Automatic bypass valve
How the designer can help?
Heating system controls should be simple to
understand and easy to adjust:
Specify a heating timeswitch that is easy to
read and set, and has a default program.
Locate the timeswitch where it is easily
visible and accessible.
Specify room and cylinder thermostats with
the usual temperate range clearly marked.
Heating controls should have a low-
temperature limit option which can be simply
set should the occupant plan to be away for
more than a day.
Any electric immersion heater fitted to the
hot water cylinder as a back-up must haveadjustable thermostatic control and a light
outside the cupboard indicating when it is
in use.
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Space heating and hot water
Energy-efficient refurbishment of existing housing (2007 edition)
6.11 Communal systems
Group, district, community, or combined heat andpower (CHP) heating systems can be installed in
suitable developments. However, consideration
needs to be given to metering, maintenance and
management arrangements.
6.12 Alternative heating systems
Individual gas room heaters with
instantaneous water heater
Given a good standard of insulation, two or three
room heaters can often supply sufficient heat for a
whole dwelling. Capital costs are low, but layout and
design must ensure adequate distribution of heat.
Warm-air heating, stored hot water
In small, well-insulated dwellings, warm-air heating
(comprising heat generator, ducts, and fans) is a
simple option. Careful design is needed for good heat
distribution and the unit must supply both space and
water heating.
A variety of renewable and low-carbon heating
systems are described on page 30.
Further Information
For more detailed guidance on space heating
and hot water please see the following Energy
Saving Trust literature:
Central Heating System Specification (CHeSS)
Year 2005 (CE51/GIL59).
Domestic heating by oil: boiler systems
(CE29).
Domestic heating by gas: boiler systems
(CE30).
Domestic heating by solid fuel: boiler
systems (CE47).
Domestic heating by electricity (CE185).
Community heating: a guide (CE55).
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Electricity for lights and appliances (including cooking)
can account for a significant proportion of total energycosts and CO2emissions. Landlords and developers
can reduce these by:
Specifying energy efficient lamps wherever
appropriate and switches at all room exits.
Encouraging gas cooking, if gas is available.
Choosing low energy appliances.
Providing occupants with information on the choice
and use of low energy lights and appliances.
Specifying onsite sustainable electricity sources
such as photovoltaics (PV).
7.1 Lighting
Energy demand for lighting can be reduced by:
Using energy efficient lamps and luminaries (light
fittings).
Directing light to where it is needed.
Controlling lighting use.
Making the most of daylight.
Immediate results can be made in the first three areas
through basic home improvements.
The greatest savings will be achieved through periodic
refurbishment work such as rewiring. Low energylighting should be installed as part of the works.
Dedicated fittings will only accept particular types
of lamp. A low energy lamp is one with a luminous
efficacy greater than 40lm/W (lumens per Watt)
luminous efficacy is a measure of the energy efficiency.
Compact and tubular fluorescent lamps both meet this
requirement. Tungsten halogen lamps do not.
These low-energy lamps have a longer life than
traditional tungsten lamps and use less energy. Many
energy efficient lamps and dedicated fittings displaythe Energy Saving Recommended certification mark.
7.2.1 Communal lighting
All communal lighting should be controlled; by time
switches, photoelectric units, push-button controls,
or Passive infra-red (PIR) presence detectors, as
appropriate. Low-energy tubes or lamps should also be
used, except where push-button time-delay switches
or PIR are installed.
7.2.2 External lighting
Exterior lighting on estates and in communal areas
should use either:
Incandescent lamps with photocells (daylight
sensors) and PIR with a maximum lamp capacity of
150W OR
Energy efficient lamps (efficacy of at least 40l/W)
and compatible photocell or timer.
Type 6Enclosed with
electromagneticballast
Type 9Triple loop/triple two-fingerwith electronic integratedballast
CFLs with integral gear (plug-in lamps)
Type 7Enclosed with eitherelectronic orelectro-magnetic ballast
Type 8Four-finger tube withsmall electronicintegrated ballast
Type 10Four-finger tube withlarge electronicintegrated ballast
Type 11 Circulartube with integratedelectronic ballast
CFLs for use with separate gear
Type 1Two-fingertube
Type 2Four-fingertube
Type 3Triple loop/tripletwo-finger tube
Type 42D shapetube
Type 5Four- fingertube
7 Energy Saving Trust technical recommendations Lights and appliances
Best practice: 75 per cent of all fixed luminaries
should be dedicated, high-frequency, low-energy
fittings.
Figure 7.1A range of CFL designs
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Lights and appliances
Energy-efficient refurbishment of existing housing (2007 edition)
7.2 Appliances
Appliances account for a large proportion of total
domestic energy use. As energy efficient appliances
use less electricity, they are less expensive to run and
are responsible for lower CO2emissions.
Appliances may be increasingly efficient, but our
homes contain more and more of them. It is very
important, therefore, to choose models that are energy
efficient. There is often very little difference in capitalcost but a great difference in running costs and CO2
emissions. Energy labelling schemes make the selection
of appliances simpler.
7.3 Energy labels
In 1995 the European Union introduced a compulsoryenergy labelling scheme for household appliances,
covering refrigerators, freezers and fridge-freezers. This
scheme has since been extended to include washing
machines, tumble dryers, washer-dryers, dishwashers,
electric ovens and lamps. Energy labels are displayed
on these products in shops and showrooms, in
order to allow potential purchasers to compare their
efficiencies.
The energy labels show estimated fuel consumption
(based on standard test results) and an energy
grading from A to G, where A is the most efficient(for cold appliances, A++ is the most efficient). An
A-rated appliance will use approximately half as much
electricity as a G-rated appliance.
However, the actual amount of electricity used will
depend on how the appliance is used and where it
is located. For example, a cold appliance (such as a
fridge) that is placed next to a heater or oven will use
more energy than one that is sited in a cooler place, so
kitchen layout is important to energy efficiency.
Some labels now also provide information on other
aspects of the performance of the appliance, e.g.washing performance, water usage per cycle, spin (for
washing machines), etc.
Best practice: specify Energy Saving
Recommended appliances
Further information
For more detailed guidance on lights and
appliances please see the following Energy
Saving Trust literature:
Energy efficient lighting (CE61).
Low energy domestic lighting (GIL20).
Low energy domestic lighting: looking goodfor less (CE81/GPCS441).
Figure 7.2 EU energy labels
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Energy-efficient refurbishment of existing housing (2007 edition) 29
Lights and appliances
Table 7.1 Typical savings
A/A+ Rated Appliances TypicalAnnual
Saving (/yr)*
Fridge Freezer (A+) 37
Chest Freezer (A+) 26
Upright Freezer (A+) 26
Refrigerator (A+) 16
Washing Machine (A) 8
Dishwasher (A) 16
*Based on an appliance purchased new in 1995
being replaced by an Energy Saving Recommended
one.
7.4 Energy saving recommended
The Energy Saving Trust manages a labelling scheme
for products of proven energy efficiency. The scheme
currently covers appliances (washing machines,
fridges, freezers, dishwashers and tumble dryers),
light bulbs and fittings, gas and oil boilers , heating
controls, loft insulation, cavity wall insulation, external
wall and dry-linings, high performance hot water
cylinders and windows.
These products carry the Energy SavingRecommended label. Currently endorsed
products can be found at
www.energysavingtrust.org.uk/recommended
7.5 Providing information
Occupants should be given clear information onchoosing low-energy appliances and energy efficient
lighting. This should focus on the labelling schemes
and is particularly important where appliances are
not provided.
For further information on giving energy efficiency
advice see the Energy Advice Handbook referenced in
the Further information section of this guide.
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8 Renewable and low-carbon technologies
Several types of renewable technologies can generate
electricity for a dwelling or community, includingphotovoltaics (PV), wind and micro-CHP.
Other renewable, or low-carbon technologies can also
provide heating and hot water, such as heat pumps,
biomass and solar hot water. These can often be
installed as part of a refurbishment project.
8.1 Photovoltaics (PV)
A PV panel will convert solar energy to electricity. Even
in cloudy, northern latitudes, PV panels can generate
power to meet some or all of a buildings electricity
demand. Installation can often be carried out with verylittle disruption to residents.
PV is a flexible and versatile technology. Panels can
be used in roofs, curtain walls and decorative screens.
PV can be used in glass roofs and in conservatories
where it will also provide some solar shading. Here,
these products serve the same structural and weather-
protection purposes as traditional alternatives, as well
as offering the benefit of power generation.
8.2 Wind power
There are many large estates where community wind
turbines (CWT) might be appropriate. However, factorssuch as local wind regimes, planning permission,
and noise levels have to be taken into account. Wind
turbines work best on relatively open sites, but modern
units on tall towers have opened up new possibilities.
8.3 Micro-CHP
Micro combined heat and power is an emerging
technology, which is expected to play a significant role
in future domestic energy provision. Micro-CHP units
are about the same size as small domestic refrigerators
or floor-mounted boilers, and are similar in appearance.
They are predominantly gas-powered, delivering
between 1-3kW of electric power (1-3kWe), and
4-8kW of heat (4-8kWth). They can therefore provide
space heating and hot water, as well as the additional
benefit of electricity generation.
In currently available systems, heat is delivered to
radiators by hot water, and domestic hot water is
supplied by a conventional indirect storage cylinder. A
micro-CHP unit can be connected into an existing wet
heating system, often as a replacement for an existing
boiler.
Dwellings are thus unlikely to require significant
alteration and disruption to the occupants isminimised.
Micro-CHP systems with higher thermal outputs
will help with hard-to-treat dwellings (those with
solid walls, solid floors and no loft space) where
there is a relatively large heat demand and energy
efficiency measures are expensive. In this case,
micro-CHP will produce fewer carbon emissions
than a condensing boiler.
8.4 Biomass
If taken from a sustainable source, biomass fuels(including waste wood sources and farmed energy
crops such as willow) are carbon neutral apart from
the small amount of CO2arising from the felling,
processing and transportation.
Wood fuels come in three main forms:
Logs.
Chips.
Pellets.
While biomass is well suited for use with wet
boiler-based heating systems, certain issues must be
addressed if replacing a gas-fired boiler.
Monitoring and maintenance
Fuel consumption must be monitored to ensure
adequate stocks. Automatic feed systems require
maintenance and the residual ash has to be removed/
disposed of.
Storage
Depending on the fuel and the regularity of deliveries,
a large fuel storage facility may be required. Wood
pellets are the most fuel dense and should be
preferred where there is limited storage space.
Supply
There are currently only a few pellet suppliers ,
although the market is expanding. Up-to-date supplier
information can be obtained from www.logpile.co.uk
Quality
There is no UK standard for pellet quality. There is,
however, a voluntary code of good practice and with
the formation of the British Pellet Club there is progress
towards standardisation.
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8.5 Ground source heat pump (GSHP)
A GSHP transfers heat from the earth to the dwellingby means of an electric heat pump. A GSHP is a low-
carbon technology, whilst it does consume electricity to
power the heat pump unit a larger amount of useful
heat is generated for every unit of electricity used.
The systems require collectors in the ground: these can
be horizontal or vertical. Horizontal collectors are more
economical but require sufficient available land near
the dwelling.
The most obvious applications are for individual
houses in rural areas away from gas mains and alsolow density urban housing with sufficient land. Groups
of small blocks of flats may also be appropriate and
GSHPs can be used to replace baseload boiler plant in
communal heating systems.
Although the heat can be distributed through large
radiators, underfloor heating is more efficient because
it operates at lower temperatures, when heat pumps
are more efficient.
8.6 Solar hot water (SHW)
SHW systems use the suns energy to produce hotwater. They are particularly appropriate where heating
system improvements are already being undertaken
and a solar collector can be fitted on the roof. The
main types of system use either flat plate collectors or
evacuated tube collectors. In both types, liquid in the
solar collector is heated by the sun. This then passes
through a coil in a hot water storage cylinder. The
water in the cylinder can be used at this temperature,
or raised to a higher temperature by a boiler or electric
immersion heater.
These systems do not generally provide space heatingand are described as solar thermal systems. They are
amongst the most cost-effective renewable energy
systems for existing dwellings. During the summer
months, a typical system can supply between 80 and
100 per cent of hot water demand, the percentage
being much lower in winter, of course.
When using SHW heating in existing housing:
Ensure an adequate area (typically 2-5m2) of
south-oriented (45) pitched roof is available (not
shaded by chimneys, dormers, etc).
Provide a larger hot water storage cylinder thanwould normally be needed for a gas-fired system.
Check whether planning permission is needed for
roof-mounted collectors, especially in conservation
areas and other architecturally sensitive locations.
Even when it is decided not to include solar water
heating, it is worth making properties solar ready,
to allow systems to be added later with minimal
disruption.
Further informationFor more detailed guidance renewable and low-
carbon technologies please see the following
Energy Saving Trust literature:
New and renewable energy technologies for
existing housing (CE102).
Renewable energy in existing homes case
studies (CE191).
Renewable energy sources for homes in
urban environments (CE69).
Renewable energy sources for homes in rural
environments (CE70).
Figure 8.1 Evacuated tube collectors
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9 Embodied energy
There is a growing urgency to reduce the
environmental impacts of human activities. Energyefficiency initiatives over the last 40 years have reduced
the energy consumption of buildings considerably,
but action to minimize the impact from construction
materials has been relatively slow.
There are two key elements to the energy use of
a building. Energy used by occupants to run the
building during its lifespan known as operational
energy; and energy used during the manufacture,
maintenance and replacement of the components
that constitute the building during its lifespan. This is
known as embodied energy.
In older buildings operational energy has
traditionally represented the major impact. As theenergy efficiency standards of modern buildings
have been raised the importance of embodied
energy has increased.
Where the selection of products and materials
directly affect the operational energy, the most
efficient option should be selected. For those
looking to maximise environmental benefit,
or where products are very similar in terms of
operational performance, then embodied energy
aspects should also be taken into consideration.
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10 Energy Saving Trust best practice guidance
The following publications can be obtained free
of charge by telephoning the Energy Saving Truston 0845 120 7799 or by visiting the website at
www.energysavingtrust.org.uk
Whole house
Domestic energy efficiency primer (CE101/GPG171)
The effect of Building Regulations Part L1 (2006)
on existing buildings (CE53)
Refurbishing dwellings a summary of best
practice (CE189)
Practical refurbishment of solid-wall houses(CE184/GPG294)
Energy efficient historic homes case studies
(CE138)
Home conversion and extensions
Energy efficient loft conversion (CE120)
Energy efficient garage conversions (CE121)
Energy efficient domestic extensions (CE122)
Insulation
Effective use of insulation in dwellings (CE23)
Insulation materials chart thermal properties and
environmental ratings (CE71)
Cavity wall insulation in existing housing - A guide
for specifiers and contractors (CE16)
Internal wall insulation in existing housing
(CE17/GPG138)
External insulation systems for walls of dwellings
(CE118/GPG293)
Advanced insulation in housing refurbishment(CE97)
Glazing
Windows for new and existing housing (CE66)
Ventilation
Energy-efficient ventilation in housing
(CE124/GPG268)
Improving air tightness in dwellings
(CE137/GPG224)
Heating
Central Heating System Specifications (CHeSS)
Year 2005 (CE51/GIL59)
Domestic heating by gas: boiler systems (CE30)
Domestic heating by oil: boiler systems (CE29)
Domestic heating by solid fuel: boiler systems
(CE47)
Domestic heating by electricity (CE185)
Lighting
Energy efficient lighting (CE61)
Low energy domestic lighting looking good for
less (CE81/GPCS441)
Low energy domestic lighting (CE188/GIL20)
Renewable energy
New and renewable energy technologies for
existing housing (CE102)
Renewable energy in existing homes case studies
(CE191)
Renewable energy sources for homes in urban
environments (CE69)
Renewable energy sources for homes in rural
environments (CE70)
Frequently asked questions
Energy efficiency frequently asked questions
(CE126)
To obtain these publications or for more information,
call 0845 120 7799
email bestpractice@energysavingtrust.org.uk
or visit www.energysavingtrust.org.uk/housing
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11 Further information
Contacts
Energy efficiency advice and grant informationThe Energy Saving Trust manages a UK-wide network
of Energy Efficiency Advice Centres (EEACs).
Telephone 0800 512 012 to be automatically
connected to the EEAC that covers your area, or visit
www.energysavingtrust.org.uk/myhome
Insulation
Cavity Insulation Guarantee Agency (CIGA)
Tel: 01525 853300
www.ciga.co.uk
National Insulation Association (NIA)Tel: 01525 383313
www.insulationassociation.org.uk
British Polyurethane Foam Contractors Association
(BUFCA)
Tel: 01428 654011
www.bufca.co.uk
Insulated Render and Cladding Association (INCA)
Tel: 01428 654 011
www.inca-ltd.org.uk
GlazingGlass and Glazing Federation
Tel: 0870 042 4255
www.ggf.org.uk
Fenestration Self-Assessment Scheme
Tel: 0870 780 2028
www.fensa.co.uk
British Fenestration Rating Council (BFRC)
www.bfrc.org
Draught-strippingNational Insulation Association (NIA)
Tel: 01525 383313
www.insulationassociation.org.uk
Draught Proofing Advisory Association Limited
Tel: 01428 654011
www.dpaa-association.org.uk
Ventilation
Residential Ventilation Associationwww.feta.co.uk/rva/
The Electrical Heating and Ventilation Association
Tel: 0207 793 3008
www.tehva.org.uk
Heating and hot water
HHIC (Heating and Hot water Information Council)
Tel: 0845 600 2200
www.centralheating.co.uk
CORGI (Council of Registered Gas Installers)Tel: 0870 401 2200
www.corgi-gas-safety.com
OFTEC (Oil-Firing Technical Association)
Tel: 0845 6585080
www.oftec.org
Heating Efficiency Testing and Advisory Service Ltd
(HETAS Ltd)
Tel: 01242 673257
www.hetas.co.uk
The Solid Fuel AssociationTel: 0845 601 4406
www.solidfuel.co.uk
The British Electrotechnical and Allied Manufacturers
Association
Tel: 020 7793 3000
www.beama.org.uk
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12 Publications
Building regulations and policy
Energy White Paper: Our energy future creating a lowcarbon economy, DTI, February 2003.
The Building Regulations 2000, Conservation of fuel
and power, are detailed in Approved Document L1B
Work in existing dwellings (2006 Edition).
See www.communities.gov.uk
Section 6: Energy, of the Domestic Technical Handbook
outlines possible ways of complying with the Building
(Scotland) Regulations 2007
See www.sbsa.gov.uk
Building Regulations (Northern Ireland) 2000, are
detailed in Technical booklet F1 2006, Conservation of
fuel and power in dwellings.
See www.dfpni.gov.uk
The Governments Standard Assessment Procedure for
Energy Ratings of Dwellings. SAP 2005.
See www.bre.co.uk/SAP2005/
Cavity wall insulation
BS 5617:1985 Specification for urea-formaldehyde (UF)
foam systems suiTable for thermal insulation of cavity
walls with masonry or concrete inner and outer leaveswww.bsi-global.com
BS 5618: 1985 Code of practice for thermal insulation
of cavity walls (with masonry or concrete inner and
outer leaves) by filling with urea-formaldehyde (UF)
foam systems
www.bsi-global.com
Ventilation
Background ventilators for dwellingsIP2/2003, BRE, 2003.
Embodied energy
BR390 The Green Guide to Housing Specification,
Anderson and Howard, BRE, 2000
Life Cycle Assessment of PVC and of principal
competing materials. Commissioned by the European
Commission, April 2004.
EcoHomes XB
The environmental rating for existing dwellings.www.breeam.org
Energy Advice Handbook
The energy advice handbook is an essential reference
book for energy advisors and those interested in
domestic energy issues.
Tel: 01457 873610
www.energyinform.co.uk
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CE83
Energy Saving Trust,21 Dartmouth Street, London SW1H 9BP Tel 0845 1
Recommended